Grinding machine



Dec. 12, 1933. B. A. KEARNS GRINDING MACHINE Filed April 4. 1932 6 Sheets-Sheet l QMWW Dec. 12, 1933. B, A. KEARNS GRINDING MACHINE Filed April 4. 1952 6 Sheets-Sheet 2 Dec. 12, 1933. B. A. KEARNS GRINDING MACHINE Filed April 4. 1932 V 6 Sheets-Sheet 3 Dec. 12, 1933. B, A, KEARNS GRINDING MACHINE 6 Sheets-Sheet 4 Filed April 4. 1952 M\ \MW Q Na Dec. 12, 1933. A, KEARN 1,938,767

GRINDING MACHINE Filed April 4. 1932 6 Sheets-Sheet 5 III I ""mlfl n...

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Patented Dec. 12, 1933 GRINDING MACHINE Bernard A. Kearns, Cincinnati, Ohio, assignor to Cincinnati Grinders Incorporated, Cincinnati, Ohio, a corporation of Ohio Application April 4, 1932. Serial No. 602,896

17 Claims. (Cl. 51-72) This invention relates to improvements in machine tools and especially to improvements in grinding machines.

One of the principal objects of the present inl vention is the provision of an improved grinding machine for expeditiously producing and finishing multiple diameter work pieces such as shafts or other cylindrical bars having a plurality of diameters throughout their length.

Another object of the invention is the provision of improved cam bar orstop bar positioning means.

Another object of the invention is the provision of improved control mechanism for the stop bar positioning means utilizing hydraulic pressure as V the control medium.

Other objects and advantages oi the present invention should be readily apparent by reference to the following specification considered in conjunction with the accompanying drawings, forming a part thereof, and it is to be understood that any modifications may be made in the exact structural details there shown and described within the scope of the appended claims without exceeding or departing from the spirit of the invention.

In the drawings:

Figure 1 is a front elevation of a grinding machine embodying the improvements of this invention. v

Figure 2 is a sectional view taken substantially on line 22 of Figure 1.

Figure 3 is a fragmentary sectional view taken in the same plane as Figure 2, but laterally spaced as respects same.

Figure 4 is a sectional view taken on line 4-4 of Figure 3.

Figure 5 is a top plan view of certain parts of the machine, other parts being in cross section and as seen from line 5-5 on Figure 3.

Figuree is a sectional view taken on line 6-6 of Figure 3. A Figure 7 is a sectional view taken on line 7-7 of Figure 2.

Figure 8 is a fragmentary sectional view taken on line 8-8 of Figure 1.

Figure 9 is a sectional view taken on line 99 of Figure 8.

Figure 10 is a sectional view taken on line l010 of Figure 8.

Figure 11 is a sectional view taken on line 11-11 of Figure 5 V Figure 12 is a fragmentary sectional view as seen from line 12-12 of Figure 2. Figure 13 is a diagrammatic view illustrating the hydraulic circuit involved in this invention.

Throughout the several views of the drawings similar reference characters are employedto denote the same or similar parts.

As was noted above, this invention has for its 00 principal object the expeditious production of multiple diameter shafts such as motor armature shafts or the like having a plurality of independent different diameter portions. In the past it was customary to manually actuate either the work support or tool support away from the particular diameter being operated upon and then advance the parts relative to one another to align the tool and next diameter, whereupon the reverse actuation was given to either the 10 work or tool to again engage the tool and succeeding diameter of the work. This operation was a slow process and very fatiguing to the operator because a plurality of turns of the tool or work support hand wheel was necessary to 76 obtain the desired clearance between the work and wheel and a similar number of turns of the wheel was necessary to again effect the engagement between the work and wheel. By this invention the grinding wheel or work support is automatically actuated toward the other and automatically retracted requiring a relatively small fraction of the previous energy expended by the operator and reducing the time involved to a.minimum. The same clearance is had at all 86 times, maintained between the grinding wheel and the work prior to the actual engagement of the wheel with the work. There has been chosen to illustrate the invention a center type grinder in which the grinding wheel is mounted for feed- 00 ing movement toward and from the workduring the grinding operation to reduce the work to the final desired size.

. As shown in the drawings. the machine comprises a bed 15 having formedon theupper sur- I6 face thereof a. guideway 18 for the work supportj ing table 17 for guiding saidtabl'e in its movement longitudinally thereof. The table 1'! ad- Justably supports, as is the usual practice, a head stock 18 and a tail stock 19 having respectively projecting therefrom centers 20 and 21 engaging the opposite terminals of the work 22. The head stock 18 is self-contained and adapted to be rotated by an electric motor or the like 23 associated therewith for rotating the work 22 during the grinding operation.

Any suitable or desirable means may be employed for translating the work supporting table 17, but as here shown, this mechanism may conveniently take the form of a hand wheel 24 having projecting therefrom a shaft 25 bearing a gear or pinion for a transmission chain or the like 26. This chain or other transmission is operatively coupled with a stub shaft 27 journaled in the bed 15 and bearing interiorly thereof a bevel gear 28 in mesh with a bevel pinion 29. The pinion 29 is secured to one end of a vertical shaft 30 journaled on the bed as by bearing lug 31 and having at its upper end a pinion 32 meshing with a rack 33 secured to the under surface of the table 17. From the foregoing, it will be noted that rotation of the hand wheel 24 through the transmission 26 and gears 28 and 29 will rotate the rack pinion 32 for translating thetable 1'7 longitudinally of the bed.

If desired, power means may be employed for translating said table for which purpose it may have depending therefrom a lug 34, see Figure 13, having secured thereto one end of a piston rod 35 carrying at its other end a-piston 36 enclosed within a suitable hydraulic cylinder 3'7. A pressure pump 38 is provided for drawing a suitable pressure fluid, such as oil, from a tank'39 through a pipe or conduit 40 and discharging same into the pipe or conduit 41 under pressure. This pipe or conduit 41 terminates ata starting and stopping valve 42. Extending from the valve 42 is a pipe or conduit 43 terminating adjacent the reversing valve 44 where the hydraulic medium is connected alternately with pipes or conduits 45 and 46 respectively terminating adjacent opposite ends of the cylinder 3'7. Use of one of the conduits 45 and 46 as a pressure conduit leaves the remaining one for a discharge conduit for connecting the used or spent hydraulic medium, through -the reverse valve 44, with either of branch discharge conduits 4'7 and 4B terminating in the starting and stopping valve 42. The starting and stopping valve 42 connects the branch discharge conduits with the main discharge conduit 49 which terminates in the tank or sump 39. The valve 44 is adapted to be automatically reversed through the movement of the table 1'7 for which purpose it has adjustably secured thereto reversing dogs 50 and 51 adapted alternately to engage the upper end of a reversing lever 52 pivoted at 53 intermediate its ends. This lever 52 terminates in a ball end 54 received in a socket or between collars 55 on the end of stem of the reversing valve 44. From the foregoing it will be seen that the movement of the table in either direction will cause one of the dogs 50 and 51 to engage and oscillate the lever 52 about its pivot 53 and thereby shift the valve 44, first in one direction and then in the other for alternately connecting the main pressure conduit 43 with the cylinder conduits 45 and 46.

As seen in Figure 2, the bed is provided with a rearward extension 56 providing guideways 57 for a grinding wheel carriage 58 movable toward and from the work 22. The carriage-s58 has journaled in bearings 59 a spindle 60 to one end of which is secured a grinding wheel 61 enclosed within a guard or hood 62. The carriage 58 is further provided with a nut 63in threaded engagement with a'screw 64 rotatably journaled at its rear end 65 in althrust bearing carried by a sliding head 66. The screw 64 is further provided intermediate its ends with'a splined portion 68 received in a. splined sleeve 69 projecting from a gear '70. This gear '70 meshes with a pinion '71 of a compound gear '72 which has its companion gear '73 meshing with a pinion '74 keyed or otherwise secured to one end of a transverse shaft 75. The shaft 75 is journaled at its rear end in a housing '76 secured in any desirable manner to the rear wall of the bed extension 56. This housing '76 has secured therein a stud 77 on which is loosely journaled the compound gear '72 and this housing is further provided with the bearing portion '78 in which is rotatably journaled the sleeve 69 of the gear '70. The transverse shaft '75 extends'from the housing '76 through the bed beyond the forward wall thereof where it is again journaled in the housing '79 secured to the forward face of the bed 15. The housing '79 encloses the/usual feed actuator and control mechanism ,indicated generally by the numeral 80 and terminating in the'cross feed hand wheel 81 and pick feed power actuated ratchet 82.

From the foregoing it will be noted that manual rotation of the handle 81 or power pick feed actuation of the ratchet 82 will through the transmission 80 rotate the shaft '75 and through the transmission gearing above described, extending between the shaft '75 and adjusting screw 64, properly rotate said screw for actuating the grinding wheel toward and from the work 22.

, The foregoing movement of the grinding wheel carriage 58 takes place during the actual feed of the grinding wheel into the Work and for compensating or adjusting the position of the grinding wheel relative to the bed and the said carriage is actuated at a rapid rate toward and from the work by the following mechanism. The sliding head 66 is enclosed within a housing or bracket 83 prcvding a guide therefor which is secured to the housing '76. The head 66 is further providedon its under surface with rack teeth 84 meshing with a rack pinion 85 on one end of pinion shaft 86 journaled in suitable bearings 8'7 and 88 carried by the lateral sides of the housing 83. The shaft 86 is further provided with a rack pinion 89 near its other end meshing with a rack bar 90 secured to or formed on a piston rod 91 movable through the aperture provided in the housing 83. Secured to the piston rod on one end thereof is a piston'92 adapted to be reciprocated through a cylinder 93 secured in any desirable manner to the forward face of the housing 83.

The cylinder 93 has extending respectively from its opposite ends a pipe 94 and 95 each terminating in a reversing valve 96, shown diagrammatically in Figure 13 as comprising cannelures 9'7 and 98 for alternately connecting the pressure and exhaust therewith. The cylinder 93 is closed at its opposite ends by cylinder heads 99 and 100 for limiting the movement of the piston therein and consequently defining the maximum zone of travel of the carriage 53 under influence of the hydraulic medium. This represents the maximum travel of the carriage which is varied in one direction by means to be subsequently de scribed so that the head 100 is rarely engaged to define the forward limit of movement of the carriage 58 while the head 99 is at all times em ployed to define the rearmost position of the said carriage. To avoid a sharp contact between the piston 92 and head 99, the piston rod 91 has projectfng from the other side of the rack portion 90 a bar or stem 101 having formed centrally therethrough a slot or way 102 through which the arm 103 of bell crank 104 projects. The bell crank 104 is pivoted at 105 to a tongue or lug projecting from a valve block 106 secured to the housing member 83. The upper end of the arm 104 is bifurcated as shown at 107 receiving between its fingers a pin projecting from a valve plug 108. Loosely surrounding the stem 101 is a collar 109 pinion is likewise imparted to the arm 121.

engaging on one end with a spring 110 surrounding the stem 101 and positioned within a pocket formed in the block 106. The stem 101 is further provided on its extreme 'end with an abutment 111 for engaging the bell crank 103 and oscillating it as the piston and parts carried thereby are actuated to the left, as seen in Figure 3.

The conduit 95 is connected through the valve 96 when actuated to the right, with the conduit 112 termna'ting in a port 113 formed in the valve block 106 which during the movement of the piston to the left, as seen in Figure. 3, is open and is gradually shut off causing the hydraulic medium, as seen in Figure 6, to travel through the ports 114 and 115 to and past the adjustable needle or choke valve 116 to the port 117 and exhaust conduit 118. As shown in Figure 13, the conduit 118 terminates in the rear end of the slide block 66 which has a control or cushioning valve formed therein for cushioning the engagement of the stop mechanism, which will be described in detail later, and which stop mechanism limits the inward travel of the grinding wheel and its carriage.

From the foregoing it will be noted that the grinding wheel carriage is actuated toward and from the work by power or hydraulic means and that the piston which'actuates said carriage is provided with a cushioning mechanism preventing the sudden engagement between the piston head 99 and piston 92.

The valve 96 is provided with a circumferential groove 119 receiving a roller 120 carried on the end of an arm 121 which surrounds the reduced portion 122 of the transverse shaft 75. The arm 121 abuts on one side with a flange 123 integral with or secured to the driving pinion 74 and on the other side with a friction washer 124. Opposed to the friction washer 124 is a second washer 125 having between them a spring 126 tensioned by means of a nut 127 on the end of the shaft extension 122. The valve 96 is enclosed within a sleeve 128 through which it is reciprocated or actuated.

The friction washers 124 and 125 and the spring 126 oo-operate to hold the arm- 121 in engagement with the flange 123 of the pinion 74 so that any movement imparted to the said The operation of these parts is as follows. Actuation of the manual lever or wheel 81 rotates the shaft for oscillating the arm 121 in the same direction as the shaft 75 is moved. As will be described in detail later, the mechanism for shifting this valve is so arranged that on retracting the grinding wheel from the work, the valve cannot be actuated for feeding the wheel toward the work until the grinding wheel has been retracted a predetermined definite amount, while as soon as the grinding wheel is retracted to the aforesaid predetermined definite point, the valve may be shifted for immediately actuating the grinding wheel toward the work.

In order to limit the approach of the grinding wheel toward the work, the housing 83 is provided with a guide 131 for a cam or stop bar' 132 which has a contour corresponding to the contour of the work and providing a plurality of stop or cam faces 133. The cam bar passes through an aperture 134 formed in the slide block 66 for aligning the several cam or stop faces 133 with a stop pin 135 carried by the extreme end of the block 66. To accommodate the pin 135 the block is provided with a perforation 136 through which it operates. The inner face of the aperture 134 adjacent the cam 132 has secured. to it -a hardened shoe 137 which abuts individually the several cam stops for actually limiting the approach of the grinding wheel and work. The cam bar 132 is stopped with one of its faces in alignment with the shoe 137 by means of stop pins or plugs 138 of which there are a plurality depending upon the number of stop faces 133 on the cam, which is in turn controlled by the contour of the work. The stop pins are actuated by hydraulic pressure and are actuated in sequential order as the table 17 carrying the work is advanced toward the left, for example, as seen in Figure 1. It is to be understood, howeventhat the said stops are also properly actuated when the work table is actuated toward the right.

To control the said stop pins 138 the table is provided on its forward face with a dog rail 139 having adjustably secured thereon a plurality of dogs 140 each positioned relative to the rail in accordance with the relative positions of the several'diameters of the work. Also mounted on the forward face of the bed 15 is a housing 141, see Figure 8, secured in any desirable manner to a bracket 142 projecting from said forward face of the bed. The bracket 142 has secured therein a shaft 143 which extends outwardly through the housing 141 and has mounted thereon a sleeve 144. The sleeve 144 is carried on suitable bushings for rotation relative to the shaft 143 and is coupled as by means of a key or pin 145 to a star wheel 146 likewise loosely journaled on the shaft 143 at its rear end adjacent the bracket 142. The star wheel 146 is provided with a plurality of fingers 147 between each pair of which is formed a groove receiving a pin 148 projecting from each of the dogs 140. As the table is advanced successive dogs have their pins enter the various slots for advancing the star wheel in a step by step manner relative to the shaft 143 for thereby rotating said star wheel and the sleeve 144.

Secured to the sleeve as by means of pins or screws 149 are a plurality of cam plates 150 each having formed therein a depression or notch 151, see Figure 9. By reference to this figure, it will be noted that the cam plates 150 bear a relation to one another such that the notch or recess 151 in successive plates 150 is advanced as respects the preceding plate so that at each step of rotation of the star wheel 146 a different cam slot is brought into play. The housing 141 supports beneath and to one side of the shaft 143 a rocker arm shaft 152 on which is oscillatably mounted a plurality of rocker arms 153, there being as many arms as there are cams 150 on the sleeve 144. Each rocker arm 153 has a nose 154 at its upper end for riding on its associated cam plate 150. The other end of each rocker arm 153 is furcated as at 155 to provide arms 156 and 157 adapted to straddle the reduced portion 158 of a valve 159. The valve 159 is adapted to be slidably actuated through a sleeve pins 148, advance the star wheel step by step for thereby rotating the sleeve 144 and bringing successive cam plates 150 into registry with their rocker arm nose 154. The spring 163 tending to oscillate the said rocker arms in a counterclockwise direction or toward the cam surfaces axially shifts the valve 159 to the right, as seen in Figure 9. i

In order to hold the sleeve 144 in its adjusted positions and to prevent inadvertent rotation of the cam plates 150, the sleeve 144 may have formed integrally with it at one end thereof or secured to it a ratchet plate 165 co-operating with a spring loaded detent 166. The detent 166 has secured to it one end of a spring 167 which tends to oscillate said detent in' a counterclockwise direction or toward the ratchet 165 and the spring 167 has its other end anchored to a plate or tie bar 168 which connects-the outer ends of the shafts 143 and 152, as will be clearly seen in Figure 10.

The valve casing is provided with as many valve sleeves 160 as there are cam plates 150 and in each sleeve is mounted a valve 159 which is provided intermediate its ends with a cannelure 169 for connecting the hydraulic pressure from the pipe or conduit 170 with the pipe or conduit 171 that extends from each of the valve sleeves 160 to one of the stop pins 138. The hydraulic pressure is directed to the cannelure 169 by means of ports 172 and 173 formed in the valve casing 161. The valve casing has further extending from it a pipe or conduit 174 which returns the used or spent hydraulic medium to the tank or sump 39.

As shown diagrammatically in Figure 13, the conduit 170 is connected with the pump pressure line 41 and is further provided with a plurality of branch pressure lines 170a which terminate in ports 172 and 173 connected with the cannelure 169 of the individual valves 150. Extending from.

each valve is a conduit 171a which terminates adjacent one of the stop pins 138. As further shown in Figure 13, each valve has extending from it a.

branch conduit 174a which connects with the main return conduit 175 terminating in the tank or sump 39.

As shown in Figure 11, each conduit 171a connects with the top of a cylinder 176 formed in a cover plate 177 secured to an intermediate member 177a in turn secured to the housing or bracket 83. The cover plate 177 carries a plurality of bushings 178, one in alignment with each cylinder, and in which bushings is mounted a spring 180. The springs 180 each surround the stem portion 179 of asto'p pin 138 carried by the intermediate member 177a andcover plate 177. The springs further-abut on' on'e end with a radial flange 178a formed lower end of said hushings and on a washer 181, pinnedorotherwisesecuredtothestemflit The stop pins 138 are each providedinterme'diate 'ing wheel toward the work, the ratchet wheel 82 138a the spring expands and withdraws the pins 138 to an inoperative position.

The stop bar 132 is provided on one end with a slot 182 receiving therein a shoe 183 pivoted by means of pin 184 to the outer end of an oscillatory arm 185 pivoted at 186 to the bracket 93. Intermediate the ends of the arm 185 it has pivotally secured as at 187 a shoe 188 received in a groove 189 formed transversely of a cross head 190 secured in any desirable manner to the outer end of a piston rod 191. This piston rod 191 is connected at its inner end to a piston 192 operable through a cylinder 193 carried by the bracket 83 and closed at opposite ends by means of heads 194 and 195. An adjustable stop 196 is carried by the head 194 to limit the movement of the piston 192 in one direction. The heads 194 and 195 each carry one end of a conduit 197 and 198, which are diagrammatically shown in Figure 13 as respectively connected with the conduits and 94. From this it will be seen that actuation of the piston 92 in a direction to feed the grinding wheel into the work automatically shifts the stop bar 132 transversely of the path of movement of the grinding wheel carriage to stop the said grinding wheel carriage before it engages the work, while reverse actuation of the piston 92 reversely shifts the piston 192 for retracting the cam bar.

In order to cushion the impact of the shoe 137 with the steps 133 of the cam bar, the plunger 135 abuts with an adJustable stop screw 199 carried by a lever 200 intermediate its ends. The lever 200 is pivoted at 201 for oscillation and is provided with fingers 202 at its one end straddling a pin 203 projecting from a valve 204 slidably mounted in'the end of the slide block 66, while the other end of the lever 200 is spring loaded as by spring 200a for returning the valve 204 to its normal position. As was noted above, and shown diagrammatically in Figure 13, the conduit 118 terminates in the end of the slide block 66, entering a port 205 formed therein. The port 205 connects with a port 206 which is controlled by the slide valve 204. A port 207 extends from the port 206 and is controlled by an adjustable needle or choke valve 208. Extending from the port 207 and controlled by the valve 208 is a conduit 209 which terminates in the tank or sump 39. The slide valves 108 and 204 are so interconnected that when the piston 92 is moving to the left, as seen in Figure 3, the valve 108 controls the movement between it and the piston head 99, as above described. When the piston 92 is travelingin the opposite direction, the plunger 135 carried by the block 66 upon engagement with one of the steps 133 of the cam or stop bar 132, actuates the valve 204 for cushioning the impact of the shoe 137 with the said cam stops or steps. From this it will be seen that the hydraulic piston 92 is always under control and prevents any jarring of the machine at either end of its stroke. In order to insure the complete rotation of the hand wheel or crank 81 in a reverse or retracting direction before again feeding the grindis provided with the usual pick feed guard 210 carried by a block 211 adapted to be secured to the ratchet wheel 82. The block 211 has pivotal- 1n order to feed the grinding wheel into the work, the ratchet 82 is actuated in a counterclockwise direction, as seen in Figure 12, which carries with it the pawl 212 causing the rounded outer surface 215 to ride on the periphery of the fixed ratchet 213. This movement continues until the work is to the desired size, which is substantially the position shown in Figure 12, at which time the pawl arm is in the dotted line position indicated by the numeral 216. The ratchet wheel 82 is then actuated in a clockwise direction, as seen in this Figure, which immediately places the pointed nose 217 of the pawl 212 on the periphery of the fixed ratchet 213 so that any reverse counterclockwise movement of the ratchet 82 will cause the said nose 217 to engage the teeth of the ratchet 213 until the ratchet 82 has been actuated to a point to allow the pawl 212 to drop into the recess 214 whereupon the ratchet 82 can be reversely actuated. At this time, however, the grinding wheel has been retracted to provide the necessary or desired clearance between the grinding wheel and the next step of the work as determined by the stop face 133.

The operation of the machine is as follows: A work piece similar to that shown in Figure 1 is mounted between the head and tail stock centers 20 and 21 and the table 1'7 advanced for example, to the left to align the smallest diameter with the grinding wheel. At this time,

the ratchet feed wheel 82 and associate parts are in the position shown in Figure 12. The ratchet wheel is then rotated in a counterclockwise direction to rotate the feed screw 64 in the direction to feed the grinding wheel into the work. Rotation of this ratchet feed wheel, however, will rotate the shaft for shifting the valve 98. The shifting of this valve connects the hydraulic pressure in theline 41 with the hydraulic cylinders containing the pistons 92 and 192 for first actuating the piston 192 to the right, as seen in Figure 4, and subsequently shifting the piston 92 to the right, as seen in Figure3. Prior to the actuation of these pistons, however, the dog 140, representing the smallest diameter of the work, actuated the star wheel 146 a distance to cause the proper cam plate 150 to align its notch 151 with the arm 153 for shifting the proper valve 159 and connecting the hydraulic pressure with the proper stop pin cylinder 178 and lowering the stop pin 138 into the path of movement of the stop bar 132.

The stop bar 132 is therefore moved through its piston 192 until the stop pin is engaged thereby aligning the lowest stop step 133 with the contact or stop shoe 137. The piston 92 is then actu-. ated until engagement between the said shoe 137 and stop step 133 is reached whereupon further movement of this piston is stopped. The feed mechanism is then thrown into operation which through the normal feed pawl operating on the ratchet 82 continues until the guard ,210 stops further automatic feed between the work' and wheel.

The parts are allowed to remain in their final grinding position for a suitable period of time to effect a sparking out between the grinding wheel and work and to provide the desired finish thereon. At the conclusion of this dwell the hand crank or wheel 81 is operated in a clockwise direction, as seen in Figure 12, for rotating the screw 64 in a direction to effect the retraction of the grinding wheel from the work. This movement oi the hand crank or wheel 81 immediately shifts the valve 96 for'connecting the hydraulic pressure in the line 41 with the ,position, the table is advanced either by the hand wheel 24 or the hydraulic piston 38 to align the next step on the work with the grinding wheel. The movement of this table 17 through v the next dog 140 rotates the star wheel 146 for rotating the cam plates 150 and aligning the notch 151 in the proper cam plate with the arm 153 and'actuating the second stop pin 138 into position for stoppingthe stop bar on its next movement. With the parts so adjusted, the grinding wheel is again fed into the work by actuating the feed ratchet 82 manually as above described, whereupon the valve 96 is again shifted for connecting the hydraulic pressure in the line 41 with the conduits 95 and 197 as above described foragain positioning the parts whereupon the second diameter is reduced to the final or desired size.

This operation is continued until all of the various diameters on the work piece have been properly ground and finished whereupon the finished work piece is removed from the machine and an unfinished or rough one substituted therefor.

In order to prevent inadvertent shifting of the stop pins 138 and to insure sufiicient time for actuation of said stop pins, the device is so arranged that the actuation of said pinstakes place only during the inward movement of the grinding wheel carriage. For this reason there is provided a cut oi! valve 225 having aspring loaded plunger valve 228, see Figure 13, adapted to be actuated, for example, by a cam 227, see Figure 3, when the grinding wheel carriage is in its retracted position. From this it will be seen that the parts are all in their neutral or starting position before being actuated to operative positions and that they are all returned to neutral position prior to each successive operativapcsition.

What is claimed is:

1. In a grinding machine of the class described the combination of a bed, a grinding wheel mounted thereon and movable relative thereto, a work supporting table mounted on the bed in the line of movement of the grinding wheel, a stop bar movable transversely in the line of movement of the grinding wheel for variably limiting the approach of the grinding wheel to the work supporting table, a plurality of hydraulically actuated piston pins for controlling the position of the stop bar, an hydraulic medium under pressure for actuating the piston pins, means for selectively connecting the medium with the piston pins to actuate same to an operative position, and yielding means for reversely actuating said pins to an work, and means for stopping the grinding wheel just short of successive portions of the work comprising a stop bar conforming substantially to the contour of the work, a plurality of hydraulically actuated piston pins for positioning the stop bar in accordance with the particular diameter of the work in line with the grinding wheel, an hydraulic medium under pressure for actuating the piston pins, means for selectively connecting the medium with the piston pins to actuate same to an operative position, yielding means for reversely actuating said pins to an inoperative position when the hydraulic medium is cut off, and means carried by the table for actuating the selecting means of the hydraulically actuated stop means.

3. In a grinding machine for grinding su'ccessive portions of a multiple diameter work piece the combination of a bed, a work supporting table for supporting the multiple diameter work piece, a grinding wheel carried by the bed and movable relative thereto toward and from the work, and means for stopping the grinding wheel just short of successive portions of the work comprising a stop bar conforming substantially to the contour of the work, a plurality of hydraulically actuated piston pins for positioning the stop bar in accordance with the particular diameter'of the work in line with the grinding wheel, an hydraulic medium under pressure for actuating the piston pins, means for selectively connecting the medium with the piston pins to actuate same to an operative position, yielding means for reversely actuating said pins to an inoperative position when the hydraulic medium is cut off, and means carried by the table for actuating the selecting means of the hydraulically actuated stop means, comprising a plurality of valves, and means on the table for individually actuating said valves.

4.- In a grinding machine for grinding successive portions of a multiple diameter work piece the combination of a bed, a work supporting table for supporting the multiple diameter work piece, a grinding wheel carried by the bed and movable relative thereto toward and from the work, and means for stopping the grinding wheel just short of successive portions of the work comprising a stop bar conforming substantially to the contour of the work, hydraulically actuated means for positioning the stop bar in accordance with the particular diameter of the work in -line with the grinding wheel, and means carried by the table for energizing the hydraulically actuated stop means, said hydraulic positioning means comprising a plurality of stop pins individually projectible into the path of movement of the stop-bar, said table controlling means comprising a plurality of spaced dogs mounted on the table, and hydraulic control means independent of the stop pins actuable by the dogs.

5. In a grinding machine of the class described the combination of a bed, a work support mounted thereon for movement longitudinally thereof, a grinding wheel support carried by the bed for movement thereon transversely thereof toward and from the bed, a stop bar for limiting the approach of the tool support and work support comprising a plurality of stop surfaces, hydraulic means for actuating the tool support toward the work support, hydraulic means for actuating the stop bar, hydraulically actuated means for variably limiting the movement of the stop bar to align individual stop surfaces of the bar with the tool support, and a single hydraulic pressure source for actuating said several hydraulic means, said pressure source and hydraulic means being so arranged as to operate in the sequence named.

6. In a grinding machine of the class described the combination of a bed, a work support mounted thereon for movement longitudinally thereof, a grinding wheel support carried by the bed'jbr movement thereon transversely thereof toward and from the work support, a stop bar for limiting the approach of the tool support and work support comprising a plurality of stop surfaces, hydraulic means for actuating the tool support toward the work support, hydraulic means for actuating the'stop bar, and hydraulically actuated means for variably limiting the movement of the stop bar to align individual stop surfaces of the bar with the tool support, said stop means comprising a plurality of stop pins, an hydraulic medium for actuating the pins to a stopping position, a valve controlling the flow of the hydraulic medium to each pin, and means for independently actuating the stop pin valves.

7. In a grinding machine of the class described the combination of a bed, a table mounted thereon for movement relative thereto and supporting a multiple diameter work piece, a grinding wheel carriage mounted on the bed for movement toward the work, means for advancing the table relative to the bed to alignindividual portions of the work with the grinding wheel, means for variably limiting the approach of the grinding wheel and work depending on the particular diameter of the work aligned with the wheel, and

control means carried by the table and bed for controlling the position of the stopping means including a plurality of valves individually actuable, and means for actuating the valves in' accordance with the position of the work on the table relative to the bed.

8. In a grinding machine of the class described the combination of a bed, a table mounted thereon for movement relative thereto and supporting a multiple diameter work piece, a grinding wheel carriage mounted on the bed for movement toward the work, means for advancing the table relative to the bed to align individual portions of the work with the grinding wheel, means for variably limiting the approach of the grinding wheel and work depending on the particular diameter of the work aligned with the wheel, and control means carried by the table and bed for controlling the position of the stopping means including a plurality of valves individually actuable, and means for actuating the valves in accordance with the position of the work on the table relative to the bed, said valve actuating means comprising a cam plate for each valve, a valve actuator co-operating with each cam plate and valve, and yielding means for shifting the valve.

9. In a grinding machine of the class described the combination of a bed, a table mounted thereon for movement relative thereto and supporting a multiple diameter work piece, a grinding wheel carriage mounted on the bed for movement toward the work, means for advancing the table relative to the bed to align individual portions of the work with the grinding wheel, means for variably limiting the approach of the grinding wheel and work depending on the particular diameter of the work aligned with the wheel, and control means carried by the table and bed for controlling the position of the stopping means including a plurality of valves individually actuable, and means for actuating the valves in accordance with the position of the work on the valve actuator co-operating with each cam plate and valve, yielding means for shifting the valve, a star-wheel for intermittent rotation and oper-,

atively connected with the cams, and dogs mounted on the table for movement therewith for intermittently actuating the star wheel.

10. In a mechanism of the class described for variably limiting the approach of a grinding wheel and work piece the combination of a support for the grinding wheel, a support for a work piece, a stop bar movable transversely of the line of movement of the grinding wheel support, hydraulically actuated stop bar positioning means including a plurality of stop pins each having associated therewith a piston, a valve for each stop' pin piston for connecting an hydraulic medium therewith, and means for individually actuating said stop bar pin piston valves.

11. In a mechanism of the class described for variably limiting the approach of a grinding wheel and work piece the combination of a support for the grinding wheel, a support for a work piece, a stop bar movable transversely of the line of movement of the grinding wheel support, hydraulically actuated stop bar positioning means including a plurality of stop pins each having associated therewith a piston, a valve for each stop pin piston for connecting an hydraulic medium therewith, and means for individually actuating said stop bar pin piston valves, including a cam for each valve, a valve actuator having an operative connection with each valve and its associated cam, and means for actuating the cams relative to the valves and their actuators for individually shifting the valves.

12. In a mechanism of the class described for variably limiting the approach of a grinding wheel and work piece the combination of a support for the grinding wheel, a support for a work piece, a stop bar movable transversely of the line of movement of the grinding wheel support, bydraulically actuated stop bar positioning means including a plurality of stop pins each having associated therewith a piston, a valve for each stop pin piston for connecting an hydraulic medium therewith, means for individually actuating said stop bar pin piston valves, including a cam for each valve, a valve actuator having an operative connection with each valve and its associated cam, means for actuating the cams relative to the valves and their actuators for individually shifting the valves, and power actuated means for intermittently rotating the cams and sequentially actuating the valves.

13. In a grinding machine of the class described the combination of a bed, a grinding wheel carriage mounted thereon for movement relative thereto, a work support on the bed for movement relative thereto transversely of the line of movement or the grinding wheel carriage, an hydraulic piston operatively connected with the carriage for effecting its movement, a stop bar having a plurality of stop surfaces for limiting the movement of the carriage, an hydraulic piston for shifting the stop bar, a plurality of piston pins for limiting the movement of the stop bar, a valve for each pin, a valve for alternately connecting an hydraulic pressure source with opposite sides of thecarriage and stop bar pistons, and means operable by the work support for actuating the piston pin valves for connecting the hydraulic pressure source with a selected piston pin.

14. In a grinding machine of the class described the combination of a bed, a grinding wheel carriage mounted thereon for movement relative thereto, a work supporton the bed for movement relativethereto transversely of the line of movement of the grinding wheel carriage, an hydraulic piston operatively connected with the'carriage 'for effecting its movement, a stop bar having a plurality of stop surfaces for limiting the'movement of the'carriage', an hydraulic piston for shifting the stop bar, a plurality of piston pins for limiting the movement of the stop bar, a valve for each pin, a valve for alternately connecting an hydraulic pressure source with 0})- posite sides of the carriage and stop bar pistons, means operable by the work support for actuating the piston pin valves for connecting the hydraulic pressure source with a selected piston pin, a common pressure line for each of the piston pin valves, and a stop valve in said common line operable by the carriage for interrupting the hydraulic pressure to the valves and thereby preventing the operation of the piston stop pins until the carriage and work support are in proper relationship.

15. In a mechanism of the class described for variably limiting the approach or a grinding wheel and work piece, the combination with a bed, a grinding wheel carriage mounted on the bed, and a work support mounted on the bed for movement transversely to the line of movement of the grinding wheel carriage, of a stop bar including a plurality of stops movable transversely to the line of movement of the grinding wheel carriage, a plurality of hydraulically actuated stop pins for limiting the movement of the bar, a valve for each pin, a housing containing the valves adapted to be secured to the forward face of the bed, a valve actuator for each valve mounted within the housing, a plurality of dogs mounted on the work support, means carried by the housing operable by the table dogs for effecting the actuation of the valve actuators, and a hydraulic pressure source connectible through the valves with individual stop pins.

16. In a mechanism of the class described for variably limiting the approach of a grinding wheel and work piece, the combination with a bed, a grinding wheel carriage mounted on the bed, and a work support mounted on the bed for movement transversely to the line of movement of the grinding wheel carriage, of a stop bar including a plurality of stops movable transversely to the line of movement of the grinding wheel carriage, a plurality of hydraulically actuated stop pins for limiting the movement of the bar, a valve for each pin, a housing containing the valves adapted to be secured to the forward face of the bed, a valve actuator for each valve mounted within the housing, a plurality of dogs mounted on the work support, means carried by the housing operable by the table dogs for effecting the actuation of the valve actuators, a hydraulic pressure source connectible through the valves with individual stop pins, and yielding means for rendering the pins inoperative when the hydraulic pressure source is cut off therefrom.

1'7. In a mechanism of the class described for variably limiting the approach of a grinding wheel and work piece, the combination with a bed, a grinding wheel carriage mounted on the bed, and a work support mounted on the bed for movement transversely to the line of movement of the grinding wheel carriage, of a stop bar including a plurality of stops movable transversely to the line of movement of the grinding wheel carriage, a plurality of, hydraulically actuated stop pins for limitin the movement or the bar, a valve for each pin. a housing containin: the valves adapted to be secured to the forwardiace of the bed, a valve actuator for each valve mounted within the housin8. a plurality of dogs mounted on the work support. means carried by the housing operable by the table dogs 

